(1) Field of the Invention
The present invention relates generally to three-dimensional braided structures, more particularly, to three-dimensional braided preform structures and rigid composites made therefrom.
(2) Description of the Prior Art
Typically, it is known to use braided preforms for composites and laminated structures. Additionally, the use of high performance fibers within multilayer preforms and composite structures is known in the art. Additionally, thermosetting, thermoplastic, ceramic, and carbon materials have been used in prior art to fuse fibers of textile structures for certain applications.
The invention is applicable to the design and manufacturing of valves for internal combustion engines, more specifically, carbonxe2x80x94carbon (CC) composite valves. The design of valves from CC composites was developed for many years with growing success due to their high thermal stability, dimensional stability in a wide range of temperatures, and low weight of the material. Typically, fibrous CC composites have low density, high durability and high elastic modulus in the directions of reinforcement. The low value of thermal expansion coefficient of CC composites, close to zero (0), allows successful use of these composites in environments of high temperature gradients and thermo-cycling, without inducing thermal stresses. CC composite parts and structures are widely used and have represented themselves well in aerospace engines applications. Anisotropic properties of CC composite materials allow one to find optimum design of parts having complex shape and working under complex stress/strain state.
Traditionally, a composite valve is made of several separate elementary parts. These separate parts have been encased by a braid, bonded, and/or mechanically interlocked with use of complex-shaped connecting features. Braiding is one of the set of technologies having been used to manufacture separate parts of the valve structures in the past. Prior art valves are described in U.S. Pat. Nos. 5,792,402, 4,433,652, and 5,094,200, are not integral structures, and consist of several parts manufactured separately and subsequently joined together to form a valve structure.
Development of a novel technology for manufacturing of integral valve structures would overcome the complex and multiple step manufacturing processes currently used in automotive industry. Further, the integration of the aforementioned separate components precludes the failure of valves by separation of said parts.
Thus, there remains a need for a three-dimensional engineered fiber preform for use as a mechanical component, more particularly, a complex shaped three-dimensional braided fiber preform formed and constructed of a unitary, integral construction including a plurality of fibers.
The present invention is directed to a complex shaped, three-dimensional engineered fiber preform having a unitary, integral and seamless structure and rigid composite structure made therefrom for use as a mechanical component, particularly for use as a valve, and method for making the preform.
In the preferred embodiment, the integral design and structure of the preform is formed by a combination of interlacing and non-interlacing fiber systems that permits variable cross-sectional area and dimensions of a complex shape from a first end to a second end along an axis, or from a stem end to a head end of a valve.
Preferably, a particular embodiment of the invention is an integral design of a carbonxe2x80x94carbon composite valve structure for engines of internal combustion, formed by set of straight and interlacing continuous reinforcing yarns with the help of the device with the combined mechanical scheme, allowing to produce various types of axis-symmetric braided architectures, including, but not limited to cylindrical, conical, and radial yarn placement to make an integral valve with continuously variable reinforcement architecture at various zones of the valve.
The present invention is further directed to a method for making a complex shaped, three-dimensional engineered fiber preform having a unitary, integral and seamless structure and rigid composite structure made therefrom.
Accordingly, one aspect of the present invention is to provide a complex shaped, three-dimensional engineered fiber preform having a unitary, integral and seamless structure and rigid composite structure made therefrom for providing increased component strength, durability, and stability.
These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings.